ConflictingModificationAppliedException

ConflictingModificationAppliedException is observed during 3 node clustering isolation test.
At the moment node is isolated, it changes to IsolatedLeader and therefore Cluster singleton services are close. Ending in ConflictingModificationAppliedException when Rib is closed before than Peers, or simultaneously, when trying to update/delete same branch.

Thus we move ClusterSingletonService to be implemented in only one place,
BGPDeployer, and he will take care to instanciate or closeintance when required.
And in the correct orded, which meas Peers first then Ribs.
Also if Rib is removed, Peers should also be removed.